3-methylbutene-1 polymer fiber

ABSTRACT

IMPROVED FILAMENTSOF 3-METHYLBUTENE-1, PARTICULARLY WITH RESPECT TO TENSILE PROPERTIES AT ELEVATED TEMPERATURES, MAY BE PREPARED BY HEAT TREATING POLYMERIC 3-METHYLBUTENE-1 PRIOR TO EXTRUSION AT A TEMPERATURE ABOVE ITS MELTING POINT TO INCREASE THE MELT INDEX ABOVE 10 AND THEN MELT SPINNING THE HEATED POLYMER THROUGH AT LEAST A 14 MIL DIAMETER SPINNERETTE AND DRAWING DOWN THE RESULTANT FILAMENT AT A RATIO OF AT LEAST ABOUT 150.

United States l atent C 3,631,160 3-METHYLBUTENE-1 POLYMER FIBER Walter J. Polestak, Summit, N.J., and Karl G. Adams,

Columbia, S.C., assignors to Celanese Corporation, New York, N .Y. N Drawing. Filed Nov. 2, 1966, Ser. No. 591,452 Int. Cl. (308E 15/04, 19/02; Dtlld 5/12 US. Cl. 26088.2 13 Claims ABSTRACT OF THE DISCLOSURE Improved filaments of 3-methylbutene-l, particularly with respect to tensile properties at elevated temperatures, may be prepared by heat treating polymeric 3-methylbutene-l prior to extrusion at a temperature above its melting point to increase the melt index above and then melt spinning the heated polymer through at least a 14 mil diameter spinnerette and drawing down the resultant filament at a ratio of at least about 150.

The present invention relates to a process for the production of 3-methylbutene-1 polymer fiber having improved tensile properties. Further, the invention relates to a process for the production of 3-methylbutene-l polymer fiber having improved elevated temperature tensile properties, and particularly improved elevated temperature tenacity.

Tenacity is the measure of the breaking strength of a fiber or yarn expressed in force per unit yarn number, usually grams per denier (g./d.).

Polymers of straight chain alkenes can be formed into useful filaments or fibers by extrusion, in heat-softened or molten form, through suitably shaped orifices with cooling of the extruded fiber material. The use of such products, however, is restricted by the low softening and melting points of the straight chain alkene polymers. In contrast, polymers of branched alkenes, and particularly polymers of 3-methylbutene-1, are higher softening and melting points, but these polymers have not heretofore been successfully converted into useful fibers. One of the main problems which has hindered commercial use of 3-methylbutene-l polymer fibers is that at moderate elevated temperatures, for example, temperatures in the range of from about 50 to 100 C., the tensile properties of the fiber deteriorate markedly.

Accordingly, the primary object of the present invention is to provide a process for improving the tensile properties of fibers obtained from 3-methylbutene-1 polymers. Another object is to provide a process for producing 3-methylbutene-1 polymer fibers having improved elevated temperature tensile properties, and particularly improved elevated temperature tenacity strength.

In accordance with the present invention, a process is provided for producing poly-3-methylbutene-1 fibers hav ing improved elevated temperature tensile properties. Initially, a 3-methylbutene-1 polymer having a melt index below 10 is subjected to a heat treatment sufficient to increase the melt index to above 10. The resulting heattreated polymer is then melt spun through an orifice having a diameter of at least about 14 mils to form a fiber, which is taken up at a drawdown of at least about 150. The resulting as-spun fiber, which refers to the fiber ice on the initial take-up roll or bobbin, has an improved elevated temperature tenacity strength.

Drawdown is the ratio of the velocity of the fiber at the initial take-up roll or bobbin to the linear velocity of the fiber at the extruder orifice outlet.

It has been found that when the poly-3-methylbutene-l is spun into a fiber according to the above process, the resulting as-spun fibers frequently have about a 20 to 50 percent greater elevated temperature tenacity (measured at about 95 C.) than poly-3-methylbutene-1 fibers spun according to the previously used processes employing no preheat treatment; and usually the as-spun fibers obtained via the present invention have substantially the maximum obtainable elevated temperature tenacity. Hence, after-drawing, either cold or hot, which is normally necessary to improve or obtain the maximum tenacity for polyalkene fibers, is made unnecessary. In fact, in

present invention causes a decrease in tenacity.

3-METHYLBUTENE-1 POLYMER As used in the present invention the term El-methylbutene-l polymer includes fiber-forming 3-methylbutene-l homopolymers and copolymers, the term copolymer meaning polymers having two or more different monomeric groups, including terpolymers and higher polymers. Comonomers which may be copolymerized with the 3-methylbutene-1 are monoethylenically unsaturated hydrocarbons, generally containing up to about 26 carbon atoms, including aromatics containing a monoethylenically unsaturated group, e.g., styrene. Preferably, the monoethylenically unsaturated comonomer is a straight chain l-alkene containing in the range of from about 5 to 20 carbon atoms, and more preferably from about 14 to 20 carbon atoms. Some comonomers within the foregoing class which may be used are n-pentene-l, n-octenel, n-tetradecene-l, nhexadecene-l, n-octadecene-l, neicosene-l, n-hexeicosene-l, or fractions containing mixtures of l-alkenes in which the average number of carbon atoms in the molecules is within the foregoing numerical ranges. For example, the comonomer may be a commercial fraction of straight chain l-alkenes containing 10 to 20 carbon atoms with an average of 15 carbon atoms. These 3-methylbutene-1 homopolymers and copolymers normally have a melt index in the range of from about 0.5 to 5.0, and normally 1.

The copolymers comprise a major amount of combined 3-methylbutene-1 and a minor amount of the combined comonomer. Generally, the straight chain l-alkene comonomers are used in an amount in the range of from about 0.5 to 20 mol percent, preferably 0.5 to 7.0 mol percent, of the total monomers employed in the polymerization mixture, and the final copolymer may contain in the range of from about 0.5 to 20 mol percent, preferably 0.5 to 7.0 mol percent of polymerized straight chain l-alkene, based on the total copolymer, the balance essentially being polymerized 3-methylbutene-1.

3 HEAT TREATMENT The poly-3-methylbutene-1 is subjected to a heat treatment to increase the melt index from a value of below 10, normally 0.5 to 5, to a melt index of above 10. Preferably, the heat treatment is sufficient to increase the melt index to a value in the range of from about to 80. The melt index values are determined according to the procedure set forth in ASTM D123 8-57T (at 330 C.).

In order to obtain the above increase in melt index the 3-methylbutene-lpolymer is heat treated in air or an inert atmosphere such as nitrogen, in any conventional type heating apparatus, at a temperature not lower than about the melting point of the polymer or higher. Normally a temperature in the range of from about 300 to 500 C., and preferably from about 320 to 360 C. is used. The time required to achieve the desired increase in melt index is dependent upon the temperature employed in the heating zone, the higher the temperature, the lower the time. Depending on the temperature used, the time of treatment may range from about several seconds, e.g., 2 seconds, to several hours, e.g., 3 hours, preferably from about 10 to 60 minutes, and more preferably from about to minutes. For example, it normally requires about 15 minutes at a temperature of about 350 C. to increase the melt index of a typical 3-methylbutene-1 copolymer from about 1 to about 15. Atmospheric pressures are conveniently used in the heat treating zones, but higher or lower pressures may be used if so desired.

The polymer heating operation may be carried out in any suitable manner, for example, the polymer may be introduced into a conventional type melt spinning appara tus and heat treated therein prior to, or essentially simultaneously with, being extruded. Preferably, the polymer is heat treated in a separate heating zone prior to being introduced into the melt spinning apparatus. For example, the polymer may be heat treated in a conventional extruder, the heat-treated polymer pelletized, and the pellets thereafter introduced into the melt spinning apparatus; or the polymer may be milled and then introduced into the melt spinning apparatus. In this manner, a more uniform heat treatment of the polymer occurs, thereby yielding a monoor multi-filament spun product having uniform physical properties, which is of particular importance in multifilament spinning to form yarn and the like.

MELT SPINNING The heat-treated 3-methylbutene-1 polymer is melt spun in any conventional type melt spinning apparatus wherein the polymer is extruded through a spinneret orifice. Generally, the spinneret orifice diameter is in the range of from about 14 to 80 mils, and preferably from about 20 to 60 mils. The ratio of the length of the orifice to the diameter of the orifice is normally in the range of from about 1:1 to 20:1, and preferably from about 5:1 to 10:1.

The spinning temperature, which is normally the tem perature of the polymer melt in the spinning apparatus, is conveniently in the range of from about 285 to 375 C., and preferably from about 320 to 360 C. While higher temperatures may be used, particularly, if the polymer heat-treatment is to be conducted essentially simultaneously with the melt spinning operation, the temperature should not be so high that the melt flow of the extruded fiber cannot be easily controlled. Extrusion pressures in the range of from about 500 to 5000 pounds per square inch will normally be sufiicient to extrude the poly-3- methylbutene-l in the above temperature range after the material has been subjected to the aforementioned heat treatment.

The polymer may be extruded into air at room temperature, or into an atmosphere of an inert gas, for example, nitrogen, argon, steam or carbon dioxide, or into a liquid such as water, acetone or methylene chloride at a temperature low enough to set the extruded material as it emerges from the spinneret orifice. If a gas, for example,

air, is used to quench the fiber, the gas may be circulated or jetted around the fiber as it emerges from the spinneret according to any of the commonly used processes. Such forced circulation results in better heat transfer and thus quicker setting of the fiber.

As the spun fiber emerges from the spinneret orifice it is taken up at a drawdown in the range of from about 150 to 8500, and preferably from about 1100 to 3300. The ability of the extruded fiber to be drawn to a high degree without breaking is governed by the heat treated polymer melt index and spinning conditions, e.g., spinning temperature and spinneret orifice diameter. Simple experimentation is required to determine the exact drawdown range to be used with each set of conditions. Preferably, the maxi-mum drawdown is used in each case since it has been found that as the drawdown is increased, the fiber tenacity strength increases, i.e., within the aforementioned orifice diameter and drawdown ranges.

In order to achieve the above drawdowns a linear takeup speed, i.e., the speed of the fiber at the initial takeup bobbin or roll, is in the range of from about 100 to 3000 meters per minute, and preferably from about 1000 to 2200 meters per minute.

The as-spun fibers or filaments on the initial take-up roll or bobbin generally have a denier in the range of from about 1 to 10. However, higher denier fibers may be obtained if so desired. If the maximum elevated temperature tenacity is desired, i.e. in the range of from about 3.0 to 4.5 g./d., measured at C., then the polymer should be heat treated to obtain a melt index value in the range of from about 10 to 25. However, when melt spinning such heat treated polymers a maximum fiber take-up speed of only about 1100 meters per minute may be used, higher speeds causing the resulting fiber to break. If higher take-up speeds, i.e., from about 1500 to 3000, are desired a melt index in the range of from about 30 to 50 or higher should be obtained. In such instances, slightly lower, but improved, elevated temperature tenacity values may be obtained.

While the above description has been directed toward the production of a mono-filament or fiber, multifilaments having improved elevated temperature tenacity may .also be obtained by the present invention by using a multi-orifice spinneret.

As a result of the above described process the product as-spun fibers either as continuous or staple fibers may be effectively utilized in a wide range of industrial, household, and apparel applications that would require addi tional elevated temperature tenacity, such as weather and mildew resistant tarpaulins, tents, bags upholstery, carpets, giaperies, sheets, blankets, suiting, gloves, socks and the The invention is additionally illustrated by the following examples.

In each of the following examples the 3-methylbutene-1 polymer Was formed into rods, and the rods melt spun in a micro-melt constant pressure extruder, actuated by a hydraulic air cylinder. Samples of the resulting as-spunfiber were collected during the spinning runs and tenacity values were obtained. The tenacity values were measured at 23 C. and 95 C. under the following conditions:

Testing machine: Instron Relative humidity: 65%

Gauge length: 3% inches Rate of elongation: 2.0 in./min.

EXAMPLE I The following Table I illustrates the effect of spinneret orifice diameter and thermal pretreatment on tensile properties for the copolymer of 3-methylbutene-1 and 1- octene, the copolymer comprising about 95.2 mol percent 'methylbutene and about 4.8 mol percent of l-octene. The 1rnselt index of the copolymer prior to pretreatment Was TABLE I Maximum tensile properties spinneret dimensions 23 C. 95 0.

Length] Diam- Elonga- Elongadiameter, Melt tion, Tensile tion. Tensile eter mil index" percent g./d. percent g./d.

I. N thermal pretreatment II. Rod placed under 2.8 mm. vacuum for 17 hours at 210 0. prior to extrusion III. Thermal pretreatment (rod held under following conditions prior to extrusion) 1 hr. at 320 C 1. 3 14 15 34 7. 3 36 3. 3 1 hr. at 320 C 5 15 40 10. 1 38 3. 1 1 hr. at 320 0 5 40 15 41 8. 6 36 4. 4 15 min. at 350 C 5 20 15 35 7. 9 36 2. 9

After thermal pretreatment.

As can be seen from the above Table I the maximum EXAMPLE IV elevated temperature tenacity was obtained when the copolymer was subjected to a thermal pretreatment and spun through the largest spinneret orifice diameter.

EXAMPLE II The following Table II compares the tensile properties obtained upon spinning at high drawdown versus spinning at low drawdowns followed by an after-drawing of the as-spun fiber. The copolymer was thermally pretreated at 320 C. for 1 hour, yielding a melt index value of about 15. The copolymer used in each of the runs comprised 95.2 mol percent 3-methylbutene-1 and 4.8 mol percent l-octene, having a melt index of 1.5.

The copolymers were each spun at 340 C. through an orifice having a diameter of 40 mils.

TABLE II Maximum tensile properties 23 C. 95 C. Aiterdraw Elonga- Elonga- Draw Draw tion, Tensile, tion, Tensile,

Drawdown Type temp, C. ratio percent g./d. percent g./

470 12-inch shoe (single draw)..." 150 1. 56 34 4. 7 31 2. 3 550- do 215 1. 15 35 4. 8 36 2. 7 148 2. 64 38 4. 0 39 1. 7 177 2. 64 38 4. 5 28 1. 7 200 2. 38 33 4. 8 33 2. 5 None None 41 8. 6 36 4. 4

EXAMPLE III TABLE IV measured at 23 C.

TABIJE III Drawdown: Tenacity g./d. 476 2.9

Tenacity at 23 C. g./d.

As-spun fiber 7.1 As-spun fiber subjected to an afterdraw through a hot bath maintained at ZOO-230 C. (silicone oil bath) 6.8 As-spun fiber subjected to an afterdraw through 40 p.s.i.g. steam 7.2 As-spun fiber subjected to an afterdraw over a hot shoe maintained at C. 5.9

The principal, preferred embodiment, and mode of operation of the present invention have been described in the foregoing specification. However, it should be understood that the invention which is intended to be protected herein may be practiced otherwise than as described without departing from the scope of the appended claims.

What is claimed is:

1. A process for the production of 3-methy1butene-1 polymer as-spun filament having improved elevated temperature tensile properties as characterized by a tenacity at 95 C. of at least 2.9 grams per denier, without afterdrawing, which comprises:

(a) heat treating 3-methylbutene-1 polymer having a melt index below 10 under conditions sufficient to increase the melt index to above 10, said temperature of heat treatment being at least as high as the melting temperature of said polymer,

(b) melt spinning the heat treated polymer through an orifice having a diameter of at least about 14 mils and a length to diameter ratio of about 1:1 to 20:1 to form a filament, and

() taking up the resulting spun filament at a drawdo wn ratio of at least about 150 to produce a filament having a tenacity at 95 C. of at least about 2.9 grams per denier.

2. The process of claim 1 wherein a copolymer comprising a major amount of 3-methylbutene-1 and a minor amount of another monoethylenically unsaturated hydrocarbon comonomer is used.

3. The process of claim 2 wherein the copolymer comprises a major amount of 3-methylbutene-1 and a minor amount of a straight chain l-alkene comonomer containing in the range of from about 5 to 20 carbon atoms per l-alkene molecule.

4. The process of claim 3 wherein the straight chain l-alkene comonomer constitutes in the range of from about 0.5 to 20 mol percent of the copolymer, the copolymer is heat treated at a temperature in the range of from about 300 to 500 C. to increase the melt index from a value in the range of from about 0.5 to 5 to a value of from about to 80, and the heat treated copolymer is melt spun through an orifice having a diameter in the range of from about 14 to 80 mils to form a fiber which is taken up at a drawdown in the range of from about 150 to 8500.

5. A process for producing poly-3-methylbutene-1 asspun filament having improved elevated temperature tenacity as characterized by a tenacity at 95 C. of at least 2.9 grams per denier, Without afterdrawing from a copolymer of from about 80 to 99.5 mol percent 3- methylbutene-l and correspondingly of from about 0.5 to mol percent of a straight chain C to C l-alkene, said copolymer having a melt index in the range of from about 0.5 to 5, which process comprises (a) heating the copolymer at a temperature not lower than about the melting point of the copolymer to increase the melt index to a value in the range of from about 10 to 80,

(b) introducing the heat treated copolymer into a melt spinning zone and extruding the copolymer as a melt through an orifice having a diameter in the range of from about 20 to 60 mil and a length to diameter ratio of about 5:1 to 10:1 to form a filament, and

(c) taking up the filament at a drawdown ratio in the range of from about 150 to 8500 to produce a filament having a tenacity at 95 C. of at least about 2.9 grams per denier.

6. The process of claim 5 wherein said straight chain l-alkene contains in the range of from about 14 to 20 carbon atoms per molecule and constitutes in the range of from about 0.5 to 7.0 mol percent of the copolymer.

7. The process of claim 5 wherein the copolymer is heat treated at a temperature in the range of from about 300 to 500 C. for a period of time in the range of from about 2 seconds to 3 hours.

8. The process of claim 5 wherein the copolymer is heat treated to increase the melt index of the copolymer to in the range of from about 10 to 25.

9. The process of claim 6 wherein the comonomer is n-hexadecenel 10. A process for the production of 3-methylbutene-1 polymer as-spun filament having improved elevated tem- 8 perature tenacity as characterized by a tenacity of at least 2.9 grams per denier at 95 C. without afterdrawing, which process comprises (a) heat treating a 3-methylbutene-l polymer having a melt index in the range of from about 0.5 to 5 under conditions sufiicient to increase the melt index to in the range of from about 30 to 50, said temperature of heat treatment being at least as high as the melting temperature of said polymer,

(b) melt spinning the heat treated polymer through an orifice having a diameter in the range of from about 14 to mil and a length to diameter ratio of about 1:1 to 20:1 to form a filament, and

(0) taking up the resulting spun filament at a drawdown ratio in the range of from about 1100 to 3300 and at a take-up speed in the range of from about 1500 to 3000 meters per minute to produce a filament having a tenacity at C. of at least about 29 grams per denier.

11. A continuous as-spun filament comprising 3-methylbutene-l polymer having a pre-extrusion melt index above'xlO, said filament having a tenacity at 95 C. of at least higher than 2.9 grams per denier and having been formed by extrusion through an orifice having a diameter of at least 14 mils at a drawdown ratio of at least 150.

12. A continuous as-spun filament comprising 3-methylbutene-l copolymer of from about 80 to 99.5 mol percent 3-methylbutene-1 and correspondingly of from about 0.5 to 20 mol percent of a straight chain C to C 1- alkene, said copolymer having a pre-extrusion melt index in the range of from about 10 to 80, said fiber having a tenacity at 95 C. of at least higher than 2.9 grams per denier and having been formed by extrusion through an orifice having a diameter in the range of from about 20 to 80 mils at a drawdown ratio of from about to 8500.

13. The filament of claim 12 having been taken-up at a drawdown ratio of from about 1100 to 3300 at a takeup speed in the range of from about 1500 to 3000 meters per minute.

References Cited UNITED STATES PATENTS 3,426,754 2/ 1969 Bierenbaum et al. l28156 3,432,590 3/1969 Papps 264210 F 3,112,300 11/1963 Natta et al 264l76 FX 3,143,584 8/1964 Roberts et al 264l76 FX 3,233,023 2/1966 Benson 264210 FX 3,330,897 7/1967 Tessier 264176 F 3,360,597 12/1967 Jones et al 264176 F 3,366,722 1/1968 Tessier 264l76 F 2,947,598 8/1960 Maragliano et a1. 264l76 F 3,013,003 12/ 1961 Maragliano et a1. 264176 F 3,048,467 8/ 1962 Roberts et a1 264210 F 3,112,301 11/1963 Natta et a1. 2,957,225 10/1960 Welch et a1 260-93.7 X 3,091,601 5/1963 Reding et al 26088.2 X 3,215,486 11/1965 Hada et al 264l76 F UX 3,325,461 6/1967 Boor 26088.2 X 3,316,226 4/ 1967 Clark et a1 260-88.2 X 3,361,859 1/1968 Cenzato 260-176 F 3,412,080 11/1968 Smith et al 260-93.7 X

FOREIGN PATENTS 636,913 2/1962 Canada 264290 244,825 11/ 1960 Australia 264210 818,100 8/1959 Great Britain 264l76 F 906,211 9/1962 Great Britain 264176 F 882,178 11/1961 Great Britain 264210 932,538 7/1963 Great Britain 264176 F 397,262 5/1964 Japan 264346 JAY H. WOO, Primary Examiner US. Cl. X.R.

26093.7; 264l76 F, 210 F 

